let getDouble = n => n * 2;
let _value = 1;
let double = getDouble(_value);

let count = {
    get value() {
        return _value;
    },
    set value(newValue) {
        _value = newValue;
        double = getDouble(_value);
    }
}

console.log(new Date().toLocaleString(), count.value, double);
count.value = 2;
console.log(new Date().toLocaleString(), count.value, double);